Alzheimer’s Cognitive Decline Slows in Advanced Age

August 30, 2012

The greatest risk factor for Alzheimer’s disease (AD) is advancing age. By age 85, the likelihood of developing the dreaded neurological disorder is roughly 50 percent. But researchers at the University of California, San Diego School of Medicine say AD hits hardest among the “younger elderly” – people in their 60s and 70s – who show faster rates of brain tissue loss and cognitive decline than AD patients 80 years and older.

The findings, reported online in the August 2, 2012 issue of the journal PLOS One, have profound implications for both diagnosing AD – which currently afflicts an estimated 5.6 million Americans, a number projected to triple by 2050 – and efforts to find new treatments. There is no cure for AD and existing therapies do not slow or stop disease progression.

“One of the key features for the clinical determination of AD is its relentless progressive course,” said Dominic Holland, PhD, a researcher at the Department of Neurosciences at UC San Diego and the study’s first author. “Patients typically show marked deterioration year after year. If older patients are not showing the same deterioration from one year to the next, doctors may be hesitant to diagnose AD, and thus these patients may not receive appropriate care, which can be very important for their quality of life.”

Holland and colleagues used imaging and biomarker data from participants in the Alzheimer’s Disease Neuroimaging Initiative, a multi-institution effort coordinated at UC San Diego. They examined 723 people, ages 65 to 90 years, who were categorized as either cognitively normal, with mild cognitive impairment (an intermediate stage between normal, age-related cognitive decline and dementia) or suffering from full-blown AD.

“We found that younger elderly show higher rates of cognitive decline and faster rates of tissue loss in brain regions that are vulnerable during the early stages of AD,” said Holland. “Additionally cerebrospinal fluid biomarker levels indicate a greater disease burden in younger than in older individuals.”

Holland said it’s not clear why AD is more aggressive among younger elderly.

“It may be that patients who show onset of dementia at an older age, and are declining slowly, have been declining at that rate for a long time,” said co-author Linda McEvoy, PhD, associate professor of radiology. “But because of cognitive reserve or other still-unknown factors that provide ‘resistance’ against brain damage, clinical symptoms do not manifest till later age.”

Another possibility, according to Holland, is that older patients may be suffering from mixed dementia – a combination of AD pathology and other neurological conditions. These patients might withstand the effects of AD until other adverse factors, such as brain lesions caused by cerebrovascular disease, take hold. At the moment, AD can only be diagnosed definitively by an autopsy. “So we do not yet know the underlying neuropathology of participants in this study,” Holland said.

Clinical trials to find new treatments for AD may be impacted by the differing rates, researchers said. “Our results show that if clinical trials of candidate therapies predominately enroll older elderly, who show slower rates of change over time, the ability of a therapy to successfully slow disease progression may not be recognized, leading to failure of the clinical trial,” said Holland. “Thus, it’s critical to take into account age as a factor when enrolling subjects for AD clinical trials.”

The obvious downside of the findings is that younger patients with AD lose more of their productive years to the disease, Holland noted. “The good news in all of this is that our results indicate those who survive into the later years before showing symptoms of AD will experience a less aggressive form of the disease.”

Funding for this research came, in part, from the National Institutes of Health (grants R01AG031224, R01AG22381, U54NS056883, P50NS22343 and P50MH08755); the National Institute on Aging (grant K01AG029218) and the National Institute of Biomedical Imaging and Bioengineering (grant T32EB005970).

Related

Fast Facts

Search This Site

Frequently Asked Questions

Get answers to your questions about Alzheimer's disease caregiving from the National Institute on Aging

2015 Alzheimer’s Disease Facts and Figures

Download the new report from the Alzheimer's Association here. Everyone with a brain is at risk. Share the facts.

Preventing Alzheimer’s Disease: What Do We Know?

Get this very useful and free report from the National Institute on Aging.

Need Help Caring for a Person with Alzheimer’s?

Get this excellent, free guide from the National Institutes on Health here.

It’s Never Too Late to Start Exercising

Regular exercise and physical activity are important to everyone. The National Institutes on Health offers many free publications to help you get started. Check them out.

Alzheimer’s Disease is Life Changing

Find an Alzheimer's caregiver support group near you from the Alzheimer's Association.

Want to Reduce Your Risk for Dementia?

The World Alzheimer Report 2014, Dementia and Risk Reduction: An analysis of protective and modifiable factors critically examines the evidence for the existence of modifiable risk factors for dementia. Get your copy here.

Understanding Alzheimer’s Disease: It’s Just Not Forgetfulness

Get the free and informative report from the BrightFocus Foundation.

Starting the Conversation . . .

. . about Health, Legal, Financial and
End-of-Life Issues with a Loved One. Please click here for a helpful brochure from Eldercare.gov.

Who's Blogging?

Jennifer Gerhold is an Alzheimer's advocate, writer, psychologist, and avid caregiver supporter from Washington state. She posts information about Alzheimer's disease and other dementias from around the world.

44 Million People in the World have Dementia Today

Every 70 seconds someone develops Alzheimer's disease. Fight back by being informed! Your Loved ones will thank you for it.

Need Some Ideas for the Weekend?

101 fun things to do with a loved one who has Alzheimer's disease or other dementias.

Early Alzheimer’s Detection Matters

Read about the 10 signs of AD from the Alzheimer's Association.

Caregiver’s Guide to Understanding Dementia Behaviors

Caring for a loved one with dementia poses many challenges. Get this free guide from the Family Caregiver Alliance. It will help.

After the Diagnosis of Dementia . . .

. . . What Happens Next? Read first-hand accounts, find support groups, learn about services, and much more from the National Institutes of Health.

Tips for Successful Communication

. . . at all Stages of Alzheimer's Disease. Need some help? Get this free booklet from the Alzheimer's Association.

Food that is Good for You and Your Brain

I Hear a Lot About the Mediterranean Diet, But What is It?

Caregiver Stress Check

Caregiving can be stressful. Take the Caregiver Stress Check from alz.org and get resources that can help.

Web-Savvy Caregivers

Get Your Caregiver Tips Here.

Get Started Today on a Better You

A simple and easy exercise program just for you from the National Institute on Aging. Try it out - you may like it.